Noble gases in karstic and thermal waters of Strimon basin (Greece-Bulgaria).

Free and dissolved noble gases were determined on samples from cold and thermal waters to characterize water sources and circulation paths in the Strimon basin. He isotopes, in particular, revealed the mixing between two major hydrologic systems: a cold, shallow one, related to the infiltration of air-saturated water in the Drama karstic area, and a thermal one, related to water circulation through deep-seated granites.